Colored couplers



Patented Nov. 30, 1948 COLORED COUPLERS Dudley B. Glass, Paul W. Vittum, and Arnold Weissber-ger, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application May'3, 1944', SerliaLNo. 533,932

7 Claims.

This invention relates to color photography and particularly to coupler compounds for use in'photographic processes.

Color-forming compounds which react with the development product of aromatic amino developing .agents to form colored images upon photographic development are well known. Generally, these color-forming compounds or couplers are colorless or substantially colorless. This lack of color is usually desirable where the coupler is to be incorporated in the emulsion layer and the unused coupler remains after formation of the colored image. When the coupler is used in the developing solution, it may be colored without detriment to the final image, and some colored couplers are known, such as paraphenylazo acetoacetanilide which was disclosed in Mannes and Godows'ky Patent 2,108,602.

We have now found a new type of coupler which may have applications in several fields. The new couplers are, in themselves, more-or less strongly colored, and during the coupling reaction, the chromophore system in the coupler is broken up with the result that the original color of the coupler is destroyed and a new dye is formed. Thus, on developing an emulsion layer containing one of these colored couplers, the coupler color is destroyed, and a new color is formed by the coupling reaction, at those points where development occurs. There is formed in this way a dye image of one color on a background 'of another color.

It is, therefore, an object of the present invention to provide a colored coupler whose chromophore system is destroyed on coupling. A further object is to provide a novel radical replacement type of chemical reaction. A still further object is to provide color couplers suitable for color correction processes of color photography. Other objects willappear from the following description of our invention.

These objects are accomplished by using as the coupler a compound having a heterocyclicsystem containing a methylene group and an adjacent carbonyl group as part of the ring structure, the methylene group having been substituted with an azo group. These compounds have the following general formula:

Where Z represents the atoms necessary to complete a cyclic structure having adjacent the.

methylene group --S, NH, :or a doubly boundcarbon atom andR representsan aromatic orheterocyclic radical.

More specifically, the compounds which we contemplate have the following structure:

00 x x CHN=NR where X represents the atoms necessary 'to complete a five-membered ring having adjacent the methylene group -S-, -N-H.-, or .a doubly bound carbon atom and His the same as before. In previous descriptions of reactive methylene compounds for color photography, it has been assumed that the .reactive methylene groin? must be unsubstituted in order for coupling with the developer to occur. We have found that the active methylene group may be substituted with an azo group and that this group is removable by the oxidized photographic developer when the azo-subs'tituted coupler is treated with the oxidized developer either in aqueous solution or in the photographic emulsion layer; Thus, the'coupler may be converted to a colored compound and the azo group readily removed from itby'means of reaction with the oxidized developing agent. This reaction appears-to proceed as follows:

according tosthewgeneral vformula above and whichz may be :used vto produce colored images according ,tozouri inventionz plienylozo zii dihydro -ketoindole (Z-pheziylazbpse'udoindoxyl)- dpyrazolone v Our compounds are intended for incorporation in silver halide emulsion layers either in single layer or multi-layer coatings. The compounds may be added directly to the emulsion as the sodium or other water-soluble salt or they may be incorporated in a coupler solvent as described in Mannes and Godowsky U. S. Patent 2,304,940 or Jelley and Vittum U. S. Patent 2,322,027. The compounds employed according to our invention may be produced by any suitable method such as by reaction of the reactive methylene compound with the appropriate diazonium compound. For example, compound No. 8 was prepared as follows:

p-I-Iydroxyaniline (5.5 g.; 0.05 mole) Was dissolved in a solution of 40 cc. of water and 15 cc. of concentrated hydrochloric acid and di'azotized at C. by the addition of 3 .5 g. (0.05 mole) of sodium nitrite. This solution was added to a solution of 16.1g. (0.05 mole) of 1(p (p-tert.- butylphenoxy) -phenyl) -3-methyl -5- pyrazolone in 200 cc. of water which contained g. of sodium hydroxide. The temperature of the reaction mixphotographic emulsion layer prior to exposure and upon development is converted into a colored image where the layer was exposed. The coupler remaininginthe' unexposed portions of the layer retains 'its'original color; and by suitable choice of the color of the original coupler and the color of the final dye image a masking or correction effect can be obtained.

Various photographic developing agents can be employed with the couplers of our invention. The

including the phenylenephenylenediamines may be substituted in the amino group as well as in the ring. Suitable compounds are diethyl paraphenylenediamine, monomethyl paraphenylenediamine, dimethyl paraphenylenediamine and para-aminophenol. These compounds are usually employed'in the salt form, such as the hydrochloride or the sulphate which are more stable than the free amines. All of these compounds have a primary amino group which enables the oxidation product of the developer to couple with the color-forming conipounds to form dye images.

The following developing solution is suitable for developing gelatino silver halide layers containing-colored couplers according to our invention.

2-amino fi-diethyl-amino toluene HCl i it will be understood that the examples and modifications set forth herein are illustrative only and that our invention is to be taken as limited only by the scope of the appended claims.

We claim: 1. The method of developing a colored image in a silver halide emulsion layer which comprises incorporating ,in said layer a coupler compound the oxidation product of the primary, aromatic ture was kept at 0 C. by the addition of ice 1 After standing for thirty minutes the cold solution was acidified with 20 cc. of concentrated hydrochloric acid. After'the product had crystallized, it was washed with water and dried in air. The yield amounted to 19 g. (86%). The product was recrystallized from acetic acid. M. P. 185187.

Our compounds are particularlyuse ful in a' process, such as that of Hanson U. S. Patent 2,449,966, granted September 21, 1948, The Hanson process involves a color correction method in which a colored coupler-is incorporated in the amino developing agent to form a dye image, leaving said coupler compound intact in the un developed regions of said layer.

2. The method of developing a colored image in a silver halide emulsion layer which comprises incorporating in said layer a coupler compound. having the formula:

/N=oNn-x' o o- H-N=N-R where R is anaryl group oi the benzene series and X? is an aromatic acid. acyl group, and said coupler compound contains/no other reactive CH- group, exposing said layer and developing it with a. primary aromatic amino developing agent,

thereby splitting ofi the -N=N-R' group in said coupler compound and coupling said coupler compound at the point of splitting with the oxidation product of the primary aromatic amino developing agent to form a dye image, leaving said coupler compound intact in the undeveloped regions of said layer.

3. The method of developing a masked magenta color separation image in a multilayer photographic element having three superposed silver halide emulsion layers, which comprises incorporating in one of said emulsion layers a coupler compound having the formula:

oo i \CH-N=NR where Z represents the atoms necessary to complete a cyclic structure in which there is adjacent the reactive CI-I group a member selected from the class consisting of -S, -NI-I-, and carbon doubly bound to an atom selected from the class consisting of (l) a carbon atom which is part of a conjugated chain linked to an electro-negatiVe atom, (2) nitrogen and (3) oxygen, and R is selected from the class consisting of aromatic and heterocyclic radicals, and said coupler compound contains no other reactive CH group, exposing said layer and developing it with a primary aromatic amino developing agent, thereby splitting off the N=N-R group in said coupler compound and coupling said coupler compound at the point of splitting, with the oxidation product o he primary aromatic amino developing agent to form a magenta dye image, leaving said coupler compound intact in the undeveloped regions of said one layer.

4. The method of developing a masked magenta color separation image in a multilayer photographic element having three superposed silver halide emulsion layers, Which comprises incorporating in one of said emulsion layers a coupler compound having the formula:

where X represents the atoms necessary to complete a five-membered ring in which there is adjacent the reactive OH group a member selected from the class consisting of S, NH, and carbon doubly bound to an atom selected from the class consisting of (1) a carbon atom which is part of a conjugated chain linked to an electro-neg-ative atom, (2) nitrogen and (3) oxygen, and R is selected from the class consisting of aromatic and heterocyclic radicals, and said coupler compound contains no other reactive CH group, exposing said layer and developing it with a primary aromatic amino developing agent, thereby splitting off the -N=NR group in said coupler compound and coupling said coupler compound at the point of splitting, with the oxidation product of the primary aromatic amino developing agent to form a magenta dye image, leaving said coupler compound intact in the undeveloped regions of said one layer.

5. The method of developing a masked magenta color separation image in a multilayer photographic element having three super-posed silver halide emulsion layers, which comprises incorporating in one of said emulsion layers a coupler compound having the formula:

where X represents the atoms necessary to complete a pyrazolone ring, and R is selected from the class consisting of aromatic and heterocyclic radicals, and said coupler compound contains no other reactive OH group, exposing said layer and developing it with a primary aromatic amino developing agent, thereby splitting ofi the N=N-R group in said coupler compound and. coupling said coupler compound at the point of splitting, with the oxidation product of the primary aromatic amino developing agent to form a magenta dye image, leaving said coupler com pound intact in the undeveloped regions of said one layer.

6. The method of developing a masked magenta color separation image in a multilayer photographic element having three superposed silver halide emulsion layers, which comprises incorporating in one of said emulsion layers a coupler compound having the formula:

where R and R, are mononuclear aryl groups and Y is selected from the class consisting of methyl and acylamino groups and said coupler compound contains no other reactive CH group, exposing said layer and developing it with a pri-- mary aromatic amino developing agent, thereby splitting off the --N=NR group in said coupler compound and coupling said coupler compound at the point of splitting, with the oxidation product of the primary aromatic amino developing agent to form a magenta dye image, leaving said coupler compound intact in the undeveloped regions of said one layer.

'7. The method of improving the color rendition of multilayer photographic materials having silver halide emulsion layers in which subtractively colored images are formed, which comprises incorporating in one of said layers a coupler compound having the formula:

where R represents a mononuclear aryl radical and R. represents a mononuclear aryl radical, exposing said material and developing it with a developer containing a primary aromatic amino developing agent.

DUDLEY B. GLASS.

PAUL W.V1TTUM.

ARNOLD WEISSBERGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,213,986 Kendall et al -1 Sept. 10, 1940 2,220,123 Schwarc Nov. 5, 1940 2,262,055 Sease Nov. 11, 1941 2,271,230 Petersen et a1 Jan. 27, 1942 2,308,023 Peterson Jan. 12, 1943 2,310,943 Dorough Feb. 16, 1943 2,334,495 Kendall Nov. 16, 1943 2,369,489 Porter Feb. 13 1945 OTHER REFERENCES Ser. No. 394,290, Bruylants a al. (A. r. c.) pub lished May 4, 1943. 

